Celia Vélez

Doxorubicin-Loaded Nanoparticles: New Advances in Breast Cancer Therapy

Doxorubicin, one of the most effective anticancer drugs currently known, is commonly used against breast cancer. However, its clinical use is restricted by dose-dependent toxicity (myelosuppression and cardiotoxicity), the emergence of multidrug resistance and its low specificity against cancer cells. Nanotechnology is a promising alternative to overcome these limitations in cancer therapy as it has been shown to reduce the systemic side-effects and increase the therapeutic effectiveness of drugs. Indeed, the numerous nanoparticle-based therapeutic systems developed in recent years have shown low toxicity, sustained drug release, molecular targeting, and additional therapeutic and imaging functions. Furthermore, the wide range of nanoparticle systems available may provide a solution to the different problems encountered during doxorubicin-based breast cancer treatment. Thus, a suitable nanoparticle system may transport active drugs to cancer cells using the pathophysiology of tumours, especially their enhanced permeability and retention effects, and the tumour microenvironment. In addition, active targeting strategies may allow doxorubicin to reach cancer cells using ligands or antibodies against selected tumour targets. Similarly, doxorubicin resistance may be overcome, or at least reduced, using nanoparticles that are not recognized by P-glycoprotein, one of the main mediators of multidrug resistance, thereby resulting in an increased intracellular concentration of drugs. This paper provides an overview of doxorubicin nanoplatform-based delivery systems and the principal advances obtained in breast cancer chemotherapy.

5-Fluorouracil derivatives: a patent review

Introduction: The fluorinated analog of uracil 5-FU is an antimetabolite, active against a wide range of solid tumors. The main mechanism of action consists in interfering with DNA synthesis and mRNA translation. However, patients treated with 5-FU display several side effects, a result of its nonspecific cytotoxicity for tumor cells. Numerous modifications of the 5-FU structure have been performed in order to overcome these disadvantages. Areas covered: In this review, the metabolic pathways, pharmacokinetics and clinical pharmacology of 5-FU are briefly introduced. Moreover, several derivatives developed and patented, including oral 5-FU prodrugs and combinations with other active compounds, are presented. Finally, new innovative methods for administration and vehiculization of 5-FU and its derivatives are described. Expert opinion: The search for less toxic 5-FU derivatives, which diminish or circumvent some of its disadvantages, has allowed the development of selective antitumor prodrugs and novel methods for tissue-specific drug delivery. Although some of these oral prodrugs are being used clinically, either alone or in combination therapy with other anticancer agents, it seems that the potential of personalized medicine, including pharmacogenomics and targeted therapy with novel 5-FU derivatives, will improve the management and clinical responses of patients treated with 5-FU-based therapy.

Regulatory systems in bone marrow for hematopoietic stem/progenitor cells mobilization and homing.

Regulation of hematopoietic stem cell release, migration, and homing from the bone marrow (BM) and of the mobilization pathway involves a complex interaction among adhesion molecules, cytokines, proteolytic enzymes, stromal cells, and hematopoietic cells. The identification of new mechanisms that regulate the trafficking of hematopoietic stem/progenitor cells (HSPCs) cells has important implications, not only for hematopoietic transplantation but also for cell therapies in regenerative medicine for patients with acute myocardial infarction, spinal cord injury, and stroke, among others. This paper reviews the regulation mechanisms underlying the homing and mobilization of BM hematopoietic stem/progenitor cells, investigating the following issues: (a) the role of different factors, such as stromal cell derived factor-1 (SDF-1), granulocyte colony-stimulating factor (G-CSF), and vascular cell adhesion molecule-1 (VCAM-1), among other ligands; (b) the stem cell count in peripheral blood and BM and influential factors; (c) the therapeutic utilization of this phenomenon in lesions in different tissues, examining the agents involved in HSPCs mobilization, such as the different forms of G-CSF, plerixafor, and natalizumab; and (d) the effects of this mobilization on BM-derived stem/progenitor cells in clinical trials of patients with different diseases.

Poly(butylcyanoacrylate) and Poly(ε-caprolactone) Nanoparticles Loaded with 5-Fluorouracil Increase the Cytotoxic Effect of the Drug in Experimental Colon Cancer

ABSTRACTThe clinical use of 5-fluorouracil, one of the drugs of choice in colon cancer therapy, is limited by a nonuniform oral absorption, a short plasma half-life, and by the development of drug resistances by malignant cells. We hypothesized that the formulation of biodegradable nanocarriers for the efficient delivery of this antitumor drug may improve its therapeutic effect against advanced or recurrent colon cancer. Hence, we have engineered two 5-fluorouracil-loaded nanoparticulate systems based on the biodegradable polymers poly(butylcyanoacrylate) and poly(ε-caprolactone). Drug incorporation to the nanosystems was accomplished by entrapment (encapsulation/dispersion) within the polymeric network during nanoparticle synthesis, i.e., by anionic polymerization of the monomer and interfacial polymer disposition, respectively. Main factors determining 5-fluorouracil incorporation within the polymeric nanomatrices were investigated. These nanocarriers were characterized by high drug entrapment efficiencies and sustained drug-release profiles. In vitro studies using human and murine colon cancer cell lines demonstrated that both types of nanocarriers significantly increased the antiproliferative effect of the encapsulated drug. In addition, both nanoformulations produced in vivo an intense tumor growth inhibition and increased the mice survival rate, being the greater tumor volume reduction obtained when using the poly(ε-caprolactone)-based formulation. These results suggest that these nanocarriers may improve the antitumor activity of 5-fluorouracil and could be used against advanced or recurrent colon cancer.

How is gene transfection able to improve current chemotherapy? The role of combined therapy in cancer treatment.

Despite advances in cancer treatment, a large number of patients eventually develop metastatic disease that is generally incurable. Systemic chemotherapy remains the standard treatment for these patients. Several chemotherapeutic combinations have proven effective in the management of cancer. Paradoxically, although the purpose of polychemotherapy is to improve the prognosis and prolong the survival of patients, it often carries considerable toxicity that causes substantial adverse symptoms. For this reason, a major goal of cancer research is to improve the effectiveness of these cytotoxic agents and reduce their adverse effects. Gene transfer has been proposed as a new strategy to enhance the efficacy of anti-tumor drugs in the treatment of intractable or metastatic cancers. In fact, the association of gene therapy and drugs (combined therapy) has been reported to increase the anti-proliferative effect of classical treatments in lung, bladder, pancreatic, colorectal and breast cancers, among others. Various especially promising therapies have been proposed in this context, including the use of suicide genes, antisense oligonucleotides, ribozymes and RNA interference. In this chapter, we review recent progress in the development of novel anti-cancer strategies that associate cytotoxic agents with gene transfer to enhance their antitumor effect.

5-Fluorouracil Derivatives Induce Differentiation Mediated by Tubulin and HLA Class I Modulation

Neoplastic cells exhibit defects in their ability to differentiate; therefore, differentiation therapy represents a viable option to control cancer growth and progression. Rhabdomyosarcomas (RMS), a malignant tumor of skeletal muscle, is the most common soft tissue sarcoma in children and is characterized by its poor response to cytotoxic treatment and significant morbidity. Since modulation of alpha-tubulin and human leukocyte antigen (HLA) class I expression has been detected during malignant transformation, we analyzed in this study the expression pattern of both kinds of proteins after the treatment with 5-FU derivatives in the human RMS RD cell line. Cytotoxic assays, scanning and transmission electron microscopy, flow cytometry and immunocytochemical analyses were used. The compounds analyzed belonged to the following three categories: (a) symmetrical bis(5-fluorouracil-1-yl) derivatives with a linker that connects the N(1) atoms of both pyrimidine moieties by means of two amide bonds; and (b) an ester with the 5-FU base. The whole structure corresponds to the terminal fragment of the molecules included in (a) and (c) 5-fluorouracil acyclonucleoside-like structures. 1-[[3-(3-Chloro-2-hydroxypropoxy)-1-methoxy]propoxy]propyl]-5-fluorouracil (2), that belongs to the class (a) produced the highest increment of tubulin and its intense capillary distribution throughout the cytoplasm. On the other hand, N,N-bis[3-(5-fluorouracil-1-yl)-3-methoxypropanoyl]-alpha,alpha;-diamino-m-xylene (5) and 2 that are included in the class (c) caused the major percentage of marked cells by the HLA class I proteins. In short, our results showed that the 5-FU derivatives increase HLA class I expression and showed greater microtubule stability with an important network of tubulin beams related with the degree of differentiation of RD cells. These results could mean a more favorable prognosis of the patients affected with these tumors.

Differentiation of intestinal epithelial cells mediated by cell confluence and/or exogenous nucleoside supplementation.

Nucleotides (NT) and nucleosides (NS) play a key role in gastrointestinal development and in enterocyte healing after tissue damage. Exogenous NT and NS may therefore represent a novel therapy for maintaining gastrointestinal tract integrity. An exogenous NS mixture of thymidine, cytidine, guanosine and inosine (T-CGI) increases the proliferation rate of rat intestinal epithelial cell line 6 (IEC-6) cells, while a mixture of uridine, cytidine, guanosine and inosine (U-CGI) reduces IEC-6 proliferation independently of necrosis or apoptosis. This study aimed to analyze the effects of exogenous NS on IEC-6 differentiation under proliferation and differentiation conditions. To this end, IEC-6 cells were treated with NS T-CGI and NS U-CGI mixtures under low- and high-density conditions. Enterocyte differentiation was also assessed by flow cytometry, Western blotting, and light, fluorescence and transmission electron microscopy. Under proliferative conditions, villin expression was reduced in all cases, but NS-treated cells showed twofold the expression observed in NS-free cultures (controls) and more frequently showed characteristics of mature enterocytes. When cells were grown after confluence, villin expression, total protein production and morphology of NS-treated cultures were more differentiated compared with the control group. Our results demonstrate that T-CGI and U-CGI mixtures promote IEC-6 cell differentiation, with no significant differences between them. Unlike previous authors, we obtained this effect in cultures without an exogenous extracellular matrix such as Matrigel, reducing the variability among independent assays.

Coexpression of intermediate filament proteins in the chick embryo heart.

We studied the distribution of intermediate filament proteins during several stages of chick embryo heart development by indirect immunofluorescence and fluorescence-activated cell surface analysis. Vimentin is the predominant intermediate filament during the early stages of cardiac genesis, while desmin appears essentially with maturation. Desmin is the main subunit protein of intermediate filaments in the mature myocyte.

The Effects of Light-Accelerated Degradation on the Aggregation of Marketed Therapeutic Monoclonal Antibodies Evaluated by Size-Exclusion Chromatography With Diode Array Detection

Research into the effects that exposure to light can have on therapeutic proteins is essential for ensuring the quality and safety of the medicines in which they are used. It is important to understand the effects of light on aggregation to help avoid undesirable colloidal instabilities, both in the original medicines and in the formats in which they are finally administered. In this study, 5 marketed therapeutic mAbs, namely bevacizumab, cetuximab, infliximab, rituximab, and trastuzumab, were investigated for this purpose. The medicines and 2 diluted preparations in 0.9 NaCl (2 mg/mL and 5 mg/mL)-commonly used in clinical practice-were subjected to controlled light-accelerated degradation. The formation of aggregates was monitored by size-exclusion chromatography. The results indicated that light induced protein aggregation. This process of protein damage was influenced above all by mAb concentration, although the particular characteristics of each mAb were also important. Photodegradation also produced the fragmentation of the mAbs. The damage caused to the mAbs as a result of light-induced aggregation and/or fragmentation was demonstrated both in the medicines and in the diluted preparation forms. These findings should be carefully considered when handling the medicines for administration and when recommending beyond-use dates in normal hospital conditions.

Influence of dimethyl sulphoxide on intermediate filament proteins in human rhabdomyosarcoma cell lines: modulation at subcellular level

SummaryThe effects of dimethyl sulphoxide have been investigated on differentiation in human rhabdomyosarcoma cell lines obtained from typically malignant, poorly differentiated tumours. The expression of cell differentiation marker proteins (desmin and vimentin) was assessed in cell lines A-204, A-673 and RD, and the modifications in expression after 3, 8 and 24 h of induction with 1.25% dimethyl sulphoxide were recorded. Protein expression in both the cytoplasm and cytoskeleton was significantly altered by treatments lasting 8 and 24 h, the most noteworthy changes being increased desmin and decreased vimentin expression. The results clearly indicate that dimethyl sulphoxide induced changes typical of differentiation in rhabdomyosarcoma cell lines A-673 and RD; less marked changes were observed in line A-204.